Synthesis of 9-alkyl-8-methoxy-8-methyl-1,3,6-trioxo-2,7-diazaspiro[4.4]nonane-4-carbonitriles

A method of synthesis of 9-alkyl-8-methyl-8-methoxy-1,3,6-trioxo-2,7-diazaspiro[4.4]nonane-4-carbonitriles consisting in the reaction of 3-amino-8-hydroxy-1,6-dioxo-2,7-diazaspiro[4.4]non-3-ene-4-carbonitriles with methanol in the presence of sulfuric acid was developed.     

Crystal structure of diethyl-1-isobutyl-9-hydroxy-9-methyl-7-phenyl-1,4-diazaspiro[4,5] decane-6,8-dicarboxylate C25H38N2O5

The reaction of diethyl-4-hydroxy-4-methyl-2-phenyl-6-oxocyclohexane-1,3-dicarboxylate with Nisobutylethylenediamine is performed and the crystal structure of this reaction product (diethyl-1-isobutyl-9-hydroxy-9-methyl-7-phenyl-1,4-diazaspiro[4,5]decane-6,8-dicarboxylate) is determined by X-ray crystallography.     

Reduction of 7-aryl-6,8-dioxo-2-oxa-3,7-diazabicyclo[3.3.0]oct-3-ene-4-carboxylic and 7-aryl-6,8-dioxo-1-oxa-2,7-diazaspiro[4.4]non-2-ene-3-carboxylic acid esters

Ethyl 7-aryl-6,8-dioxo-2-oxa-3,7-diazabicyclo[3.3.0]oct-3-ene-4-carboxylates and ethyl 7-aryl-6,8-dioxo-1-oxa-2,7-diazaspiro[4.4]non-2-ene-3-carboxylates were selectively reduced with sodium tetrahydridoborate at the carbonyl group in the β-position with respect to the oxygen atom in the isoxazole ring.